The present invention relates to foam generating and dispensing devices and, more particularly, to manually-operated atomizing dispensers having the capacity to spray a foamable liquid as a foam.
Foam generating and dispensing devices are well known in the art, as demonstrated by the numerous patents and disclosures that have been published on this subject and by the vast array of foam product dispensers currently on the market. Recent trends in the packaging and merchandising of consumer goods, such as cleaning and waxing products, toiletries and cosmetics, foodstuffs, and the like, have evidenced a growing demand for such devices, especially those which can be held in the hand and readily operated by the household user.
The demand for these devices has heretofore been satisfied almost exclusively by the disposable, self-contained aerosol dispensers, due to their convenience and adaptability to a wide variety of products and foaming conditions. However, the continued use of such self-contained aerosol dispensers is presently being reevaluated, due in part to recently espoused environmental concern over the effect of some of the propellants used therein and in part to changing economic conditions. Accordingly, workers in the art have embarked upon a search for an acceptable replacement for the aerosol foam dispensers.
Generally, those replacement devices which have been proposed are of the type which include a collapsible bottle and a foam-forming cap assembly. The foam-forming cap assembly typically includes a homogenizing element of sponge-like material providing minute tortuous passages in which a flow of foamable liquid and air from the container is mixed to provide foam. Exemplary devices of this type are described in U.S. Pat. No. 3,985,271; U.S. Pat. No. 3,973,701; U.S. Pat. No. 3,937,364; and U.S. Pat No. 3,572,590. In such devices, the mixture of air and liquid loses considerable velocity as it passes through the homogenizing element. Consequently, such devices undesirably have only limited "reach", i.e., they require the user to dispense the foam in near proximity to the surface upon which the foam will be deposited. Furthermore, because the user must apply his efforts to expel both liquid and air simultaneously, appreciable energy is wasted in forming and dispensing the foam. Still further, such devices are uneconomical inasmuch as they require that the bottle be only partially filled with a foamable liquid so that the necessary internal air supply is available for foam formation.
Consequently, attempts have been made to convert a conventional manually-operated atomizing dispenser (or "pump sprayer" as they are often called) to a foam-forming device, thereby overcoming some of the disadvantages of the "collapsible bottle" foamers. Specifically, it has been appreciated that (a) a pump sprayer is highly efficient, i.e., the user's efforts are directed to expelling only liquid, thereby minimizing the labor involved in its operation, and (b) it has considerable "reach", i.e., the liquid can be projected over a considerable distance.
One means of converting a pump sprayer to a foam sprayer which has been suggested is a foam-generating nozzle attached to the spray outlet end of the pump sprayer. An example of such a nozzle is described in U.S. Pat. No. 3,946,947 (Schneider). Schneider utilizes an elongated, pressure-reducing passageway in which air is mixed with a foamable liquid. The foam is formed by the air/liquid mixture striking the surfaces of the passageway, i.e., turbulent flow.
The commercially acceptable quality of foam which is desired by Schneider and others is an aerosol-type foam, i.e., a foam which stays or hangs on a vertical surface to optimize contact between the foam and the surface. The initial foam pattern on the surface is maintained for several seconds without substantial drip or run.
However, the Schneider means of achieving this quality foam has several limitations to marketplace acceptance: a relatively high cost, complex nozzle attachment, reduced size of spray pattern produced, and increased user effort required to operate the pump sprayer because of the added resistance/pressure of generating the foam in the nozzle attachment.
Accordingly, it is an object of the present invention to provide a hand-held, manually-operated foam generating and dispensing apparatus which requires only minimal user effort, which has considerable reach without reducing the spray pattern, which can spray a foam of commercially acceptable quality, and which can be economically produced by conventional fabrication techniques.
More specifically, it is an object of this invention to provide a pump sprayer or manually-operated atomizing dispenser having the capacity to spray a foamable liquid as a foam.